1. Field of the Invention
This invention relates to superabrasive tools such as wheel segments which comprise a superabrasive grain such as diamond, cubic boron nitride (CBN) or boron suboxide (BxO).
2. Technology Review
Conventionally, the cutting of hard materials such as granite, marble, filled concrete, asphalt and the like is achieved with the use of superabrasive saw blades. These segmented saw blades are well known. The blade comprises a circular steel disc having a plurality of spaced segments. The segments of the tools contain superabrasive grain dispersed randomly in a metal matrix. The performance of these segmented tools is measured by examining the speed of cut and tool life. Speed of cut is a measurement of how fast a given tool cuts a particular type of material while tool life is the cutting life of the blade.
Unfortunately, the performance of these segmented abrasive cutting tools requires a tradeoff. The tradeoff is that generally it is found that the quicker cutting blades have a shorter life while the longer life blades cut quite slowly. With conventional blades this results because the matrix which holds the abrasive grain has a large impact on speed of cut and blade life.
With metal bonds for example, a hard matrix such as iron bond holds the abrasive grains better, improving the life of the blade. This increases the life of each individual abrasive grain by allowing them to dull and thereby reduce the speed of cut. Conversely, for example a softer matrix such as a bronze bond allows the abrasive grains to be pulled out of the matrix more easily thereby improving the speed of cut. This decreases the life of each abrasive grain by allowing for exposure of new sharp abrasive grains more readily at the cutting surface.
The object of the present invention is therefore to produce a segmented superabrasive tool wherein both the speed of cut and tool life are improved. A further object of this invention is to produce an superabrasive segment wherein the superabrasive grains are preferentially concentrated to achieve these results.